(1) Field of the Invention
This invention relates generally to submarines having at least one internal hydraulic system with pressure and return lines connecting a source of hydraulic pressure to various hydraulically operated devices outside the vessel's hull. More specifically, this invention deals with an external hydraulic system operated from the internal hydraulic system through a novel power piston/cylinder and slave piston/cylinder together with a simplified external hydraulic system that does not require a pump and other components for regulating the hydraulic fluid in the external system.
(2) Description of the Prior Art
A submarine generally has two hydraulic systems with cross connect lines which can be opened in the event that one should be inoperable for any reason. Both such systems operate the internal components of the submarine such as valves and emergency closure devices or the like.
An external hydraulic system is independently operated from the two internal systems. Externally operated hydraulic components outside the vessel's hull run the risk of contaminating the hydraulic fluid with seawater or other foreign material picked up by the external hydraulic components. Thus, an external hydraulic system with all the necessary hydraulic pump and control components is required in addition to the submarine internal systems.
Mechanically connected pistons operating in the same or tandem cylinders represents one approach to achieving a pumping action either for compressed air applications as suggested in U.S. Pat. No. 1,281,490 or more recently in U.S. Pat. No. 4,830,583. These prior art patents fail to show or to suggest that the fluid being handled by the one piston be so isolated from the fluid being handled by the second piston that the latter fluid can never contaminate the fluid in the power cylinder.
Double acting tandem piston pumps for providing booster pressures or to effect pulsating pressure in a second fluid are also known from prior art patents such as U.S. Pat. No. 4,674,958 and No. 3,700,360.
Somewhat more relevant but still falling short of suggesting the invention disclosed and claimed in the present application are U. S. Pat. Nos. 3,649,136, 3,790,310, and 4,223,706. These patents do suggest tandem piston cylinders mechanically connected by means of a common piston rod for operation in separate cylinders whereby separate fluids can be handled in each fluid system. U.S. Pat. No. 3,649,136 shows in FIG. 3 a control system whereby the power piston is reciprocated at a predetermined rate. There is no suggestion in this prior art patent of providing for piston movement solely to maintain a predetermined pressure in the secondary fluid. So too, U.S. Pat. No. 3,790,310 suggests that the power piston be reciprocated cyclically at a known rate to provide compressed air to a receiver. This air compression function is similar to that suggested in U.S. Pat. No. 1,281,490, and fails to show or suggest the concept of providing an isolated secondary hydraulic fluid system at least partly in the environment outside of a submarine's pressurized hull so as to achieve maintenance of a known pressure in the secondary hydraulic system that may be subjected to contamination as for example by seawater at one or more actuators associated with components external to the vessels hull U.S. Pat. No. 4,223,706 is similar to the system described in U.S. Pat. No. 3,649,136 whereby reciprocation of the tandem piston/cylinder combination is provided for in a cyclical fashion in at a predetermined rate rather than to achieve a predetermined pressure in a secondary hydraulic system that includes at least a portion thereof outside the protected environment inside the vessel itself.
Finally, U.S. Pat. No. 4,473,751 shows a tandem piston/cylinder arrangement for achieving cyclical motion of a piston rod which rod is used to provide relatively small amounts of electrical power through corresponding motion of an armature in a magnetic field such that electrical energy can be utilized in an environment which would otherwise be hostile to the hydraulic fluid in the tandem piston/cylinder setup. This disclosure merely shows the tandem piston arrangement used as a pump for a single fluid, and the isolation achieved is only as a result of transmitting motion of the piston rod to the armature of an electromagnetic machine. There is no secondary hydraulic system provided in the hostile environment as shown and described in the subject application.